Nuclear Services
Legacy Support for Safety Systems

Legacy Support for Safety Systems

Ultra has been involved in identifying at replacement solutions for Civil Nuclear operators throughout the UK. Such replacement systems are subject to the full rigour of modern standards, which were not in place when the original C&I infrastructure was put in place. In many cases the underlying architecture of the original system is not compatible with modern standards either in terms of redundancy, diversity or product integrity. This makes like-for-like replacements unsuitable and leads to significant difficulties in establishing the necessary architecture and safety requirements for replacement solutions. In particular the following issues are common challenges:


  • A significant proportion of the components in use within current systems are now obsolete
  • While not subject to lifetime limits, component ageing is usually a concern, particularly in the context of station lifetime extension programmes
  • Design disclosure from COTS suppliers for replacement equipment is often inadequate to provide a robust safety justification based on equivalence.
  • COTS products are subject to peremptory change and have an uncertain lifetime
  • COTS products sometimes fail to provide the required accuracy and electrical characteristics


Ultra has developed a range of methodologies for addressing such issues. We are capable of working at a high level to develop approaches and methodologies that balance licencing and qualification costs with equipment costs and longevity. However, the staff involved also have the skills to deal with the detailed design and qualification of replacement equipment. Typically this can be at a technology equivalence level or by mimicking the overall functionality using technologies that minimise on-going obsolescence such as hybrid circuits.